CHICAGO - With more than a foot of snow on the ground Monday across much of Illinois, temperatures plummeted to record-breaking and dangerous levels, prompting scores of schools to close, causing hundreds of traffic accidents and triggering searches for the homeless to protect them from the life-threatening cold.

At least two people in Illinois, one in Bloomington and the other in Chicago, suffered fatal heart attacks while shoveling snow Sunday. Officials said the bitterly cold temperatures on Monday likely caused two trains to hit what are called bumping posts as they pulled into a downtown station, one with enough force to send six people to area hospitals to be treated for minor injuries.

Monique Bond, a spokeswoman for the Illinois State Police, said there were no reports of traffic fatalities, despite hundreds of incidents in which vehicles spun out of control, rolled into ditches or overturned, leaving thousands of motorists stranded for as long as eight hours before they were rescued.

In Chicago, officials said efforts to find homeless people and convince them to go to shelters or warming buses appeared to be working. The Cook County medical examiner's office said there were no reports of any exposure deaths.

Some parts of the state, including Chicago, reported Monday was the coldest day since records start being kept in 1870, according to the National Weather Service. By Monday morning, temperatures at O'Hare International Airport dropped to 16 degrees below zero - two degrees below Chicago's previous record for the date, set in 1894 and matched in 1988, said Charles Mott, a weather service meteorologist. The wind chill made it feel like it was more than 40 degrees below zero.

He said to the north in Rockford, temperatures had fallen to 18 degrees below zero.

"This is some of the most extreme weather we've seen in Chicago in decades," Mayor Rahm Emanuel said at an afternoon press briefing.

Around the state, the winds, snow and cold added up to conditions treacherous enough that airlines canceled 1,600 flights at O'Hare Monday. Across town at Midway International Airport, airlines canceled some 85 more.

On the roadways, the biggest rescue operation came at the intersection of Interstates 57 and 70 near Effingham in southern Illinois when over the course of about six hours, workers plucked 375 vehicles and six semi-tractor trailers from the snow, with the larger trucks pulled out by a 10-ton Illinois National Guard vehicle.

Meanwhile, the Southern Illinois men's basketball team was forced to spend the night on the floor of a central Illinois church after the team's bus got stuck in snowdrifts on Interstate 57.

"There were accidents everywhere because of the ice," said Giovanni Lucero, a commercial painter who drove to downtown Chicago Monday morning. "It was like 'Ice Road Truckers' out there," he said, referring to a television show.

Page 2 of 2 - Gov. Pat Quinn issued a disaster declaration and, along with various law enforcement agencies, urged people to stay off the roads rather than deal with snow drifts and ice-covered pavement that had snarled interstates and shut down all together many roads. Some school districts, including Chicago's, said schools would remain closed on Tuesday.

Quinn's office said the governor had instructed most state employees to stay home, except for those in 'critical government functions." And the weather prompted the state's Department of Corrections to put eight prisons on some form of lockdown.

In Chicago, even those who stayed out of their vehicles found themselves victims of the weather, including people on a Metra train.

It was clear in the city that many people hadn't even ventured outside to get to work. There was very little traffic on the normally busy streets and only a few people on the sidewalks, looking pudgy from all the layers of clothes and a bit like bank robbers with their hats pulled down low over their heads and scarves pulled over their faces.

Jeffery Davis, 51, decided that between a heater at his house that didn't work so well and drafty windows that seemed to invite cold air inside he was better off sitting in a warm doughnut shop for a full three hours to wait for the nearby library where he works to open its doors.

"I never remember it ever being this cold," said Davis, who put on two pairs of pants, "at least three sweatshirts," two hats, "the thickest socks you'd probably ever find" and boots to make the train trip downtown from his South Side home. "I'm flabbergasted."